Rugar, D.
Mamin, H. J.
Sherwood, M. H.
Kim, M.
Rettner, C. T.
Ohno, K.
Awschalom, D. D.
Article History
Received: 8 June 2014
Accepted: 6 November 2014
First Online: 22 December 2014
Competing interests
: The authors declare no competing financial interests.